Means for eliminating or reducing the influence of disturbing-currents on telephone-circuits.



No. 886,581. PATENTED NOV. 20, 1906 O. M. JACOBS.

MEANS FOR ELIMINATING OR REDUCING THE INFLUENCE OF DISTURBING CURRENTS ON TELEPHONE CIRCUITS.

APPLICATION FILED JAN, 27, 1906.

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UNITED STATES CHARLES MARK J ACOBS.

PATENT OFFICE.

OF READING, ENGLAND.

MEANS FOR ELIMINATING 0R REDUCING THE INFLUENCE OF DISTURBING-CURRENTS 0N TELEPHONE- CIRCUITS.

Specification of Letters Patent.

Patented Nov. 20, 1906.

Application filed January 2'7, 1906. Serial No. 298.231.

T0 at whom it may concern.-

Be it known that I, CHARLES MARK JA- coBs, telegraph engineer, a subject of the King of Great Britain, residing at St. Outhberts, Alexandra Road, Reading, in the county of Berks, England, have invented a certain new and useful Means for Eliminating or Reducing the Influence of Disturbing- Currents on Telephone-Circuits, of which the following is a specification.

This invention relates to telephone apparatus subject to disturbing influence from currents foreign to those which produce speech in the telephone-receiver, and particularly to telephonic apparatus employed simultaneously on the same wire or wires with telegraphic apparatus. In this latter case when, as is usual, a single wire and earth return is employed, the telephonic apparatus is sub jected to disturbing-currents induced in the wire by neighboring wires in a manner well known in addition to the disturbing influence of the telegraphic currents on the line itself.

It has already been suggested (see, for instance, United States Patent Specification No. 7 77,324, granted to Charles Adams-Randall, December 13, 1904) to place a shunt or derived circuit around a telephone-receiver upon submarineand underground cables, such circuit including a coil of small ohmic resistance and considerable inductance and an adjustable or variable resistance, the object being to shunt the earth currents from the receiver-coil through the derived circuit, which does not stop them because of its low resistance, whereas the impedance of this circuit prevents the telephonic currents from passing that way.

It has been discovered that in using an inductance in this manner in shunt to the receiver a very much better effect is attained if the receiver be wound with aso-called phonop ore-coil-that is to say, a pair of insulated coils each of which is in inductive relationship to the other and has a free end. With a receiver so wound, the shunt-circuit con taining the inductance may even be omitted.

The invention is illustrated in the accompanying drawings, in which Figure 1 is a diagram representing the arrangement wherein a shunt is used, and Fig. 2 is a like diagram in which the shunt is .omitted.

In both figures the speaking-circuit is connected inductively with the line and includes a battery a, transmitter I), switch 0, and primary d. The secondary coil 6 is in the line connecting the main conductorf with earth.

In Fig. 1 the telephone-receiver is wound with a phonopore-coil m, and around the receiver is a circuit containing the coil n of high inductance. In this arrangement the phonopore-winding of the receiver-coil m increases the selective effect of the arrangement as compared with that of a receiver having an ordinary inductive winding, the facility of passage of low-frequency currents through the receiver-circuit being thereby still further reduced without affecting the.

passage therethrough of the telephonic currents.

In Fig. 2 the shunt-circuit containing the inductance n is omitted. the conductive resistance and the capacity of the phonoporewinding m being alone sufficient to reduce the disturbing effect of currents having fre-' quencies considerably less than those of telephonic currents, while freely permitting the passage of currents of high frequency.

What is claimed as new is 1. Means for eliminating or reducing the influence of disturbingcurrents on a telephone-receiver in a telephone-circuit, consisting of a phonopore-winding on the receiver,

the phonopore-winding and the receiver-winding being one winding.

2. Means for eliminating or reducing the influence of disturbing-currents on a telephone-receiver in a telephone-circuit, comprising a phonopore-winding on the receiver, the phonoporewinding and the receiver winding being one winding, a shunt-circuit to the receiver, and an inductive coil in the said shunt-circuit. In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

CHARLES MARK JACOBS. Witnesses:

JOSEPH MILLARD,

WALTER J. SKERTEN. 

